(1) Field of the Invention
The present invention relates to a lubricant for a thermoplastic resin and a thermoplastic resin composition comprising this lubricant. More particularly, the present invention relates to a lubricant having excellent properties such that, when the lubricant is incorporated in a thermoplastic resin such as a vinyl chloride resin, a polycarbonate resin, a polyester resin, an ABS resin, a styrene resin, a methacrylic resin or a polyethylene resin, a thermoplastic resin composition showing excellent flowability and release property at the molding step and providing a molded article having a good gloss and transparency is obtained without an adverse affect on the characteristics inherently possessed by the thermoplastic resin.
(2) Description of the Related Art
Thermoplastic resins, especially vinyl chloride resins, have excellent physical and chemical properties and thus are widely used.
Nevertheless, vinyl chloride resins have a problem in that the processability in a broad sense is poor, and although plasticizer, a processing aid composed mainly of methyl methacrylate, a lubricant or the like has been used for solving this problem, a general solution cannot be obtained by this method.
As means for solving this problem, improved vinyl chloride resin compositions have been proposed in U.S. Pat. No. 3,925,510.
In the proposed vinyl chloride resin compositions, maintenance of the transparency possessed by the vinyl chloride resin and improvement of the processability such as the drawdown effect, the flowability at the molding step, the elongation at a high temperature, the release property from the roll surface at the calendering step, and the long-period durability of lubricating properties are intended, and certain effects are attained.
Nevertheless, in view of the improvement of the productivity and quality, and to obtain an energy-saving effect, it is desirable to develop a vinyl chloride resin having a high durability of lubricating properties at the processing step and capable of providing a molded article having a good gloss and transparency, and the proposed compositions were still unsatisfactory. Moreover, an increase of substances adhering to the mold and the like (plate-out) occurs under certain molding conditions, and the proposed compositions cannot completely satisfy the market requirements.